Derating

I completed wiring the first and second floor of my house several months ago. While looking through the forums, I came across the topic of derating. I have (4) 12-2 cable running through my basement joists. Is this acceptable? I wired my entire house in 12 guage wiring, even though all outlets are 15 amp. I just wanted the thicker wiring for safety and future electrical needs. Also, does the thicker wire on 15 amps reduce the risk of fire?

The code says that you need to de-rate for any more than 4 current carrying conductors. That is two x-2 cables.

Due to the method used for de-rating this is actually not a problem on #12 or #14 wire until you have 5 or more bundled together.

In addition if you put #12 wire on 15 amp breakers, you have de-rated.

Yes, if you limit the current on any wire to a lower value, you will build up less heat. In my opinion, if you were to do a cost/benifit analisis, there is no need to use #12 where #14 is allowed by code, but it sure cannot hurt.

It was not clear from you post, but please keep in mind, that it is the breaker that limits the current to 15 amps, not the recepticle.